Synthetic-Wavelength Carrier Squeezing Interferometry with the Additive-to-Multiplicative Moiré Fringe Transition in Simultaneous Dual-Wavelength Interferometry
Simultaneous dual-wavelength interferometry(SDWI)supplies a better solution to extend the measurement range of traditional single-wavelength interferometry with higher efficiency.However,to decompose the needed longer beat-frequency synthetic-wavelength(λs)information is rather arduous from the envelope of the generated additive Moiré fringe in SDWI.In this study,a synthetic-wavelength carrier squeezing interferometry(SCSI)method is proposed to retrieve the synthetic-wavelength phase from the additive Moiré fringe pat-tern.By additive-to-multiplicative Moiré fringe transition,the interferometric information of λsis independent and appeared as the superpo-sition of other wavelengths interferometric information in the obtained multiplicative Moiré fringe pattern.Subsequently,4-frame synthetic-wavelength interferogram with π/2 phase shift could be extracted from the spectrum of the multiplicative Moiré fringe pattern.Finally,the extracted 4-frame interferogram are rearranged and combined into a single spatial-temporal fringe(STF).By converting the temporal phase shift into spatial carrier,the measured phase of λscould be retrieved by the filter and inverse Fourier transform from the spectrum of STF.And compared with traditional dual-wavelength spatial-domain Fourier transform demodulation theory,the necessary linear carrier in SCSI method is merely about 0.127 times of the former even though without the elimination of background.The feasibility and applicability of the SCSI method are verified using simulation and experimental results.
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